The South Australian government will try to change serious and high-risk offender legislation to ensure Snowtown murders accomplice Mark Raymond Haydon can be supervised when he completes his jail sentence.

Haydon is one of four men who were jailed over the Snowtown murders, also known as the "bodies-in-the-barrels" killings.

The 65-year-old is due for release in May after spending 25 years behind bars for assisting the murderers in covering up the crimes.

The government said it will introduce laws tomorrow to broaden the definition of serious and high-risk offenders to include people who assist in murders and sexual crimes, or in covering them up.

Attorney-General Kyam Maher has applied to the Supreme Court to have Haydon placed on an extended supervision order, which could restrict where he lives and what he does.

Haydon is not automatically deemed a high-risk offender under current laws.

Legal experts have said that, if the court does not designate Haydon as high risk, authorities would be powerless to stop his release — with no restrictions or supervision — at the end of his sentence.